Titanium alloys



United States Patent TITANIUM ALLOYS Earl F. Swazy, Richard H. Freyer,and Lee S. Busch, Indianapolis, Ind., assignors, by mesne assignments,to Mallory-Sharon Titanium Corporation, Indianapolis, Ind., acorporation of Delaware No Drawing. Application September 4, 1953,Serial No. 382,183, now Patent No. 2,786,756, dated March 26, 1957,which is a division of application Serial No. 138,516, January 13, 1950,now Patent No. 2,661,286, dated December 1, 1953. Divided and thisapplication February 15, 1957, Serial No. 644,433 g 4 Claims. (Cl. 7175.5)

This invention relates generally to alloys of titanium and hasparticular reference to alloys consisting of titanium, carbon andsilicon, alone, or in combination with another element, to form aquaternary alloy with titanium predominating. This application is adivisional application of Serial No. 382,183, filed September 4, 1953,now Patent No. 2,786,756, dated March 26, 1957, which in turn is adivision of application Ser. No. 138,516, filed January 13, 1950, nowPatent No. 2,661,286, dated December 1, 1953. I

An object of the present invention, therefore, is to provide wrought,ductile alloys of titanium.

Another object of the present invention is to provide a wrought, ductilealloy of titanium, carbon and silicon.

Still another object of the invention is to provide quaternary alloys oftitanium.

Yet another object of the invention is to provide alloys of titaniumconsisting of titanium, carbon and silicon having greater resistance tooxidation at elevated temperatures than pure titanium and exhibitinggood hardness characteristics thereof.

Another object of the invention is to provide an alloy of titaniumconsisting of titanium, carbon and silicon and any one of the followingelements: aluminum, copper, vanadium, chromium, boron, tungsten andiron.

Yet another object of the invention contemplates a method of preparingquaternary alloys of titanium consisting of the ternary alloys ofcarbon, silicon and titanium, to which is added an element from thegroup; aluminum, copper, chromium, vanadium, boron, tungsten or iron.

The invention, in another of its aspects, relates to the novel featuresand principles teaching the objects of the invention and to the novelprinciples employed herein whether or not these features and principlesmay be used in said object or in said field.

It is found that alloys of titanium, silicon and carbon with titaniumpredominating as a ternary alloy, or as an alloy to which may be addedanother element such as aluminum, chromium, copper, vanadium, boron,tungsten or iron provides a resistance to oxidation at elevatedtemperatures greater than that of pure titanium. Such alloys provideductile, strong alloys of titanium and exhibit good corrosion resistanceand high hardness characteristics at elevated temperatures. These alloysare usually manufactured by melting and casting in a graphite retortunder an inert or neutral atmosphere; for example, argon, or in avacuum. Further, the alloys may also be prepared by powder metallurgymethods. Thus, as an example, alloys containing .1% to 10% silicon, .2%to 2% carbon with the balance titanium, as compared to pure titanium,are characterized by having a higher tensile strength, equivalentductility, slightly higher electrical resistivity, much .992% S111-.477% Car: con-.47% bon-B al- Carbonlance Tita- Balance nium TitaniumUltimate Tensile Strength 105, 000 121, 500 Elongation in 2-.. 12. 5 12.5 Resistivity X1O- 76.5 10- Moreover, alloys, such as above, arecharacterized by a unique response to heat treatment. Upon quenchingfrom 1000" C., these alloys do not harden appreciably (most alloys oftitanium which contain metals forming stable carbides do harden onquenching). However, as the tensile strength is lowered to 113,500 p. s.i., the elongationincreases to 16.5%. In the as forged condition, thehardness at 600 C. increases from 0 Rockwell A to 32 Rockwell A whenquenched. These changes are apparently caused by the presence of largeamount of B titanium (body centered cubic) which is not transformed to aon fast cooling from 1000 C.

Again, in resistance to scaling tests at 900 C., an alloy containing992% silicon was three times as effective as that for titaniumcontaining .47% carbon. The results revealed a .536% increase in weightfor the silicon alloy and 1.89% for the titanium alloy containing carbononly.

As stated, the ternary alloys formed of titanium, silicon and carbon maybe combined with one of the elements: aluminum, copper, chromium,vanadium, boron or tungsten to form quaternary alloys. Thus, such analloy consisting of titanium, copper, silicon and carbon exhibits thecharacteristics recited previously for the above alloys; i. e.,ductility, high resistance to oxidation, better corrosion resistance,higher hardness, etc.

These alloys (titanium, copper, silicon and carbon) may be manufacturedby melting and casting under an inert or neutral atmosphere (forexample, argon) er in a vacuum. The alloys may also be prepared bypowder metallurgy methods. A preferred method would thus consist inmixing copper and silicon, in massive or powder form, with titanium insponge or powder form and melting and casting in graphite. The source ofthe carbon is the crucible and the amount is easily controlled byvarying the time that the charge is molten. The alloys are preferablyforged in air at temperatures between 300 C. and 900 C. but may be hotor cold worked by the usual methods known to the art.

The quaternary alloys of titanium, copper, silicon and carbon, hereindescribed, may be made containing small but significant amounts ofcopper, silicon and carbon: for example, up to 10% copper; up to 10%silicon; and up to 2% carbon with the balance being titanium. The lowerlimit for these alloys is 0.1% copper; 0.1% silicon; 0.1% carbon and thebalance titanium. A practical range of composition may be 1% to 5%copper; 0.5% to 3% silicon; 0.3% to 0.7% carbon and the balancetitanium.

Such alloys prepared by this invention have the following minimumproperties:

The-following chart is useful in depicting the constituents of theabovedescribed alloys.

A'lloy table While the present invention as to its objects is merelyillustrative and not exhaustive in scope and since many widely difierentembodiments of the invention may be made Without departing from thescope thereof, it is intended that all matter contained in the abovedescription be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Alloys containing from 0.1% to 10% copper, from 0.1% to 5% silicon,from 0.1% to 2% carbon, and the balance being substantially alltitanium.

2. Alloys containing from 0.1% to 10% copper, from 0.1% to 5% silicon;from 0.1% to 2% carbon and the balance being substantially all titanium,said alloys being quench hardenable and susceptible to precipitationheat treatment.

Anny Ti Si C, 3. Alloys of titauiumas in claim 2 having thefollowpercent percent percent 111g minimum propert1es:

(1) Ti, Si, o 99. 7-88 .110 .2-2 AS (3) Ti, S1, O on 99. 7-78 1-10 1-21- 10%Cl1 Quenchgd As Hot tromtiQO Forged C. to Thus, it is seen that bythe present invention primary, 1,100- 0. ductile, ternary alloys oftitanium, silicon and carbon may be formed presenting characteristicssubstantially Ultimate Tensile Strength .p. s. 1-. 125,000 150,009 f t tElongation in 2 peroent 8 3 supeilorto pure t1tar1ium 1n matters 0 resisance o OX1 a- Modulus f Elasmltynfl mp, in m lsxmt tion, resistance tocorrosion and high hardness. In add1- Electrical Reslstlvity X tion,these ternary alloys may be combined with copper. Thus, a basic ternaryalloy consists of from .1% to 10% 4. Alloys as described in claim 3characterized by hardsilicon; from .2% to 2% carbon with the remainderbeing nose at elevated temperatures up to 600 C. in excess ofsubstantially all titanium. Again, an alloy, according to this inventionmay be fabricated of titanium, silicon, carbon and copper. In such analloy, silicon and copper each may be present in amounts up to 10%;carbon up to 2%; with the remainder thereof being titanium.

those of titanium containing carbon only or of pure tita nium.

No references cited.

1. ALLOYS CONTAINING FROM 0.1% TO COPPER, FROM 0.1% TO 5% SILICON, FROM0.1% TO 2% CARBON, AND THE BALANCE BEING SUBSTANTIALLY ALL TITANIUM.